I've noticed that there are notifications now if a programme is taking too much ram and the kernel kills it.
Were they there before or it's an update from the DE or notification manager.
That's not a kernel notification, that's a program you have installed setup to monitor for oom kernel notifications then to kill the offending process before it causes system issues. I installed one ages ago as I hit oom quite a bit with some of the data analysis I do in python.